Saturday, April 05, 2014

tried tuning the C14

Tried to improve the collimation of the Celestron 14" telescope.

7:15 PM. I made a Duncan collimation mask for the C14 out of corrugated cardboard. Made it hodge-podge with minimal tools. Scissors and carpenter's square. Without a protractor. No idea if it would work.

Briefly considering using Stellarium on the Dell laptop, so to monitor the whole sky. But then TheSky 6 can do the job, when in Zenith mode. No point adding more software.

Realised I would need to use the standard configuration for controlling the Paramount, i.e. use Taurus, to control the 'scope. To then use John Phil for camera control, the monitoring, beside the OTA, during the collimation process. Hooked up the serial data cable to the Dell. Homed the Paramount with Software Bisque's app.

Chose Capella for the collimation star. Up high.

Tilted the 'scope back some more, for clearance. Tried to open the roof. Experienced the roof contactor problem. Huh. No issues the night before. Hit the motor shell (with the small counterweight) and it worked. Decided to stop at the 50% mark. Thinking it would put more weight middle pier. Stopped about one foot away. Had to coaxed the motor before moving again. Grrr. After a few more seconds, I stopped again. Bingo.

8:20. Reacquired Capella. Centred with medium power eyepiece. The wind was gusting a bit as I attached the camera. Hmm.

8:23. Noted the pattern from the focusing mask. Shot a photo. Canon 40D, f/11, ½ second, ISO 1600.

8:28. Felt cold. Realised that being on the observing floor would require more layers. Headed to the house. Returned with three more layers, including the red coat.

Took the netbook out to the telescope. Removed the red film and dropped the screen brightest. Put the small computer on a chair while I stood on the ladder so to reach the Bob's Knobs. Camera was powered with the DC coupler. The Canon USB cable between camera body and computer.

8:35. All set up. Ready to collimate. Saw the outward lines in the collimation mask but found it really hard to nail it. When the lines switch from the curved to the outward is very close to the perfect focus. Tried a few times and gave up. Reverted to the traditional means, with the mask, diffraction rings, inward and outward focus. Later used to Optec to avoid mirror shift.

Astonishing sensitive the collimation screws.

I think it is a tiny bit better. But the seeing was not good at all... I should probably have another go at it.


Forgot about the recommendation of being at 400x with the Duncan mask. That's for visual use, the recommendation, of course.

ST3P says the field is 19'29" x 12'58" with the 40D. The software says the field is 18'20" x 12'12" with the 13mm. That's like 300x. Didn't think to put the doubler in...

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